Simple enzymatic method for determining 1,5-anhydro-D-glucitol in plasma for diagnosis of diabetes mellitus.

Abstract

We have developed a simple method for determination of 1,5-anhydro-D-glucitol in plasma, based on use of pyranose oxidase (EC 1.1.3.10), an enzyme with specificity toward pyranoid compounds such as 1,5-anhydro-D-glucitol and glucose. Plasma samples deproteinized with trichloroacetic acid are passed through a two-layer mini-column packed with strongly basic anion (OH- form, the upper layer) and strongly acidic cation (H+ form, the lower layer) exchange resins. 1,5-Anhydro-D-glucitol is efficiently recovered in the flow-through fraction, which is almost devoid of other sugars that are sensitive to pyranose oxidase. The hydrogen peroxide formed in the enzymatic oxidation of 1,5-anhydro-D-glucitol is detected by a standard method utilizing an enzymatic color-developing system. The overall assay system is highly specific for 1,5-anhydro-D-glucitol. The correlation between results obtained in the present method (x) and in the gas-liquid chromatographic (GLC) method (y) was: y = 1.062x-0.293 mg/L (r = 0.997, n = 49, Sxy = 10.78 mg/L). Compared with GLC, our method is simpler in the sample treatment step and quicker in the measuring step. The precisions of the two methods are comparable.

Improved diabetes control by using ‘close adjustment algorithms’

“…Diabetic indices were measured as follows: HbA 1C by high-performance liquid chromatography, fructosamine by a colorimetric nitroblue tetrazolium method, and 1,5-anhydroglucitol by an enzymatic method. 15 Total cholesterol (TC), triglycerides (TG), HDL cholesterol (HDLC), LDL cholesterol (LDLC), apolipoprotein AI (ApoAI), apolipoprotein B (ApoB), and lipoprotein(a) (Lp(a)) were measured as described previously. 16 Leptin was measured with a conventional radioimmunoassay kit (Linco Research, St. Louis, MO, USA).…”

Plasma anhydro‐d‐glucitol (1,5‐AG) as an indicator of hyperglycaemic excursions in pregnant women with diabetes

“…The plasma concentration of 1,5-AG was measured using a modified column enzymatic method described previously [16,17]. Briefly, 100 µ l plasma was deproteinized with trichloroacetic acid and passed through a two-layer micro-column packed with ion-exchange resins (cationite Dowex 50WX8; anionite Dowex 1 × 8, Sigma, Steinheim, Germany) to remove glucose.…”

Clinical application of the serum 1,5‐anhydroglucitol assay method using glucose 3‐dehydrogenase

“…Various biochemical methods for 1,5-AG diagnosis have been developed, with pyranose oxidase-based systems currently being the most widely utilized for clinical analysis (5,6). Since pyranose oxidase is not selective toward 1,5-AG, pretreatment of serum specimens is necessary to remove glucose, which is another substrate of the enzyme.…”

“…Furthermore, G3DH is highly reactive toward 1,5-AG, with a relative activity 72% of that with glucose (7). In contrast, pyranose oxidase reacts with 1,5-AG with a relative activity of only 19% compared with glucose (5). These advantageous features of G3DH encouraged us to develop a novel enzymatic method for the determination of 1,5-AG in serum.…”